Friday, July 13, 2012

Reducing early elective delivery leads to more deaths

You could have seen this coming.

In a flourish of righteous zeal, the March of Dimes went on record strongly opposing early elective delivery before 39 weeks gestation. They railed against the increase in NICU admissions; they railed against the increase in C-sections; and they railed against the increase in costs. What they inexplicably failed to take into account was the inevitable increase in stillbirths.

When the Christiana Care Health System in Delaware implemented the March of Dimes recommendations, NICU admissions decreased, C-section rates decreased and cost decreased. And more babies died.

All singleton deliveries 37 or more completed gestational weeks during the periods of interest were included. Any fetal death was considered a stillbirth; all others were considered live births and were analyzed separately. Each stillbirth was verified and cause of death determined by review of the hospital medical record by the study investigators...

We assessed change in obstetric practice by determining the percentage of neonates delivered during the early term if the delivery was at 37 or 38 weeks compared with full term if the delivery was 39 or more completed weeks...

We had three primary neonatal outcomes for this study: admission to the NICU for at least 24 hours, fetal macrosomia, and stillbirth...

What did they find?

The new policy achieved the objective of lowering births prior to 39 completed weeks gestation:

... the overall percentage of deliveries during the early term fell from 33.1% to 26.4% (P<.001) after the guidelines were introduced when compared with before. This changed for the cohort overall and for both cesarean and vaginal deliveries. The magnitude of the change was greater for those women with an induced labor and repeat cesarean delivery; the change was greatest for those undergoing an electively induction of labor...

NICU admissions dropped:

The overall rate of admission to the NICU was significantly different between the two periods; before the intervention, there were 1,116 admissions (9.29% of term live births), whereas after, there were 1,027 (8.55% of term live births) and this difference was significant (P=.044). Multivariable logistic regression revealed a reduced odds of a NICU admission (adjusted OR 0.92, 95% CI 0.84–1.01) after the intervention...

But the stillbirth rate more than tripled:

... The overall rate of stillbirth of nonanomalous fetuses differed between the periods with an overall increased risk of stillbirth after the intervention (relative risk 2.14, 95% CI 0.87–5.26, P=.06); this overall increase was not statistically significant. However, stratification by gestational age group of the stillbirth revealed the increased risk in the after group was limited to stillbirths before 39 weeks, which increased from 2.5 to 9.1 per 10,000 term pregnancies (relative risk 3.67, 95% CI 1.02–13.15, P=.032), whereas there was no change in risk of stillbirth at 39 weeks or more (relative risk 0.91, 95% CI 0.23–3.64, P=.896).

Because this increase in stillbirths is so large, the authors reviewed each stillbirth to be sure that they were not the result of risk factors that would have triggered a medically indicated induction.

The authors carefully reviewed the medical records of each stillbirth to identify cause of death and the presence of a maternal risk factor ... No definitive cause-of-death pattern emerged.

The reduction in early elective delivery achieved the aims for which the March of Dimes advocated. The reduction in early elective delivery reduced NICU admissions, reduced both the induction rate and the C-section rate, and (although the authors did not measure this) presumably reduced costs. However, these benefits were achieved at a very steep price. The stillbirth rate increased from 2.5 to 9.1 per 10,000 term pregnancies. Instead of 3 stillbirths between 37-39 weeks among 12,000 patients, there were 11 stillbirths between 37-39 weeks among a similar number of patients after reduction in early elective deliveries.

This finding is not unexpected. CDC data shows that the stillbirth rate rises from approximately 3 per 10,000 at 37 weeks to 4.5 per 10,000 at 39 weeks. An increase of 6 stillbirths in a population of 12,000 women is almost exactly what you would expect from reducing deliveries between 37-39 weeks.

This brings us to the heart of the matter. We have traditionally approached the inherent dangers of childbirth by attempting to reduce perinatal mortality. Our efforts have been so successful, that we have turned our attention to reducing perinatal morbidity under the assumption that any reduction in morbidity would be added on to the existing reductions in mortality.

That assumption in clearly not justified. That's because low rates of perinatal mortality have been achieved, in part, by exchanging mortality for morbidity. There are fewer deaths when you deliver babies before 37-39 weeks (whether for indicated or elective reasons); those babies who otherwise would not have lived experience relatively mild, self limited problems related to borderline prematurity. Attempts to reduce these morbidities by preventing borderline premature delivery may simply result in the deaths of these babies, not an overall improvement in outcomes. That's certainly what the existing data on stillbirths and gestational age would predict and that's precisely what happened in this study.